diff --git a/openbsc/tests/gtphub/Makefile.am b/openbsc/tests/gtphub/Makefile.am
index dcb7211..137924d 100644
--- a/openbsc/tests/gtphub/Makefile.am
+++ b/openbsc/tests/gtphub/Makefile.am
@@ -1,24 +1,40 @@
-AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include
-AM_CFLAGS=-Wall -ggdb3 $(LIBOSMOCORE_CFLAGS)
+AM_CPPFLAGS = \
+	$(all_includes) \
+	-I$(top_srcdir)/include \
+	$(NULL)
+
+AM_CFLAGS = \
+	-Wall \
+	-ggdb3 \
+	$(LIBOSMOCORE_CFLAGS) \
+	$(NULL)
 
 EXTRA_DIST = \
-	gtphub_test.ok
+	gtphub_test.ok \
+	$(NULL)
 
 if HAVE_LIBGTP
 if HAVE_LIBCARES
-noinst_PROGRAMS = gtphub_test
+noinst_PROGRAMS = \
+	gtphub_test \
+	$(NULL)
 endif
 endif
 
-gtphub_test_SOURCES = gtphub_test.c
+gtphub_test_SOURCES = \
+	gtphub_test.c \
+	$(NULL)
+
 gtphub_test_LDFLAGS = \
 	-Wl,--wrap=gtphub_resolve_ggsn_addr \
 	-Wl,--wrap=gtphub_ares_init \
-	-Wl,--wrap=gtphub_write
+	-Wl,--wrap=gtphub_write \
+	$(NULL)
 
 gtphub_test_LDADD = \
 	$(top_builddir)/src/gprs/gtphub.o \
 	$(top_builddir)/src/gprs/gprs_utils.o \
 	$(LIBOSMOCORE_LIBS) \
-	-lgtp -lrt
-
+	-lgtp \
+	-lrt \
+	$(NULL)